Preliminary studies have demonstrated that enzyme activities from oral bacteria can degrade anionic proteins from human parotid and submandibular gland saliva. Several of the modified proteins are proline-rich. In addition, it was discovered that the enzyme PZ-peptidase is produced in large amounts by oral streptococci and actinomycetes. The specific objectives of this proposal are: 1. To determine by microbiological methods the bacteria in human saliva and plaque which are able to produce significant quantities of PZ-peptidase and other enzymes with the capacity to modify gland saliva proteins. 2. To purify by biochemical fractionation methods, such as affinity chromatography, the PZ-peptidase and other protease activities from specific oral bacteria. 3. To test the effect of purified PZ-peptidase and other proteases on the proline-rich proteins in parotid gland saliva. The substrate specificity of PZ-peptidase and the known sequence of amino acids in the proline-rich proteins makes it likely that such cleavage occurs. To determine if protease from oral bacteria are able to modify saliva proteins known to be involved in regulating the ecology of the oral flora and cell-associated proteins believed to be involved in heterotypic bacterial adherence. The long term goal of the proposed investigations is to evaluate the functioning of indigenous bacterial proteases in dental plaque formation and the survival of odontopathic bacteria in the oral cavity.